Use Literal to improve SpooledTemporaryFile (#3526)

* Run black code formatter on tempfile.pyi
* Use Literal to improve SpooledTemporaryFile

Previously, SpooledTemporaryFile was always an AnyStr.
Now, we load a SpooledTemporaryFile[bytes] if we open in bytes mode,
and we load a SpooledTemporaryFile[str] if we open in str mode.

stdlib/3/tempfile.pyi

@@ -55,7 +55,6 @@ def TemporaryFile(
     prefix: Optional[AnyStr] = ...,
     dir: Optional[_DirT[AnyStr]] = ...,
 ) -> IO[Any]: ...
-
 @overload
 def NamedTemporaryFile(
     mode: Literal["r", "w", "a", "x", "r+", "w+", "a+", "x+", "rt", "wt", "at", "xt", "r+t", "w+t", "a+t", "x+t"],
@@ -93,17 +92,48 @@ def NamedTemporaryFile(
 # It does not actually derive from IO[AnyStr], but it does implement the
 # protocol.
 class SpooledTemporaryFile(IO[AnyStr]):
-    def __init__(self, max_size: int = ..., mode: str = ...,
-                 buffering: int = ..., encoding: Optional[str] = ...,
-                 newline: Optional[str] = ..., suffix: Optional[str] = ...,
-                 prefix: Optional[str] = ..., dir: Optional[str] = ...
-                 ) -> None: ...
+    # bytes needs to go first, as default mode is to open as bytes
+    @overload
+    def __init__(
+        self: SpooledTemporaryFile[bytes],
+        max_size: int = ...,
+        mode: Literal["rb", "wb", "ab", "xb", "r+b", "w+b", "a+b", "x+b"] = ...,
+        buffering: int = ...,
+        encoding: Optional[str] = ...,
+        newline: Optional[str] = ...,
+        suffix: Optional[str] = ...,
+        prefix: Optional[str] = ...,
+        dir: Optional[str] = ...,
+    ) -> None: ...
+    @overload
+    def __init__(
+        self: SpooledTemporaryFile[str],
+        max_size: int = ...,
+        mode: Literal["r", "w", "a", "x", "r+", "w+", "a+", "x+", "rt", "wt", "at", "xt", "r+t", "w+t", "a+t", "x+t"] = ...,
+        buffering: int = ...,
+        encoding: Optional[str] = ...,
+        newline: Optional[str] = ...,
+        suffix: Optional[str] = ...,
+        prefix: Optional[str] = ...,
+        dir: Optional[str] = ...,
+    ) -> None: ...
+    @overload
+    def __init__(
+        self,
+        max_size: int = ...,
+        mode: str = ...,
+        buffering: int = ...,
+        encoding: Optional[str] = ...,
+        newline: Optional[str] = ...,
+        suffix: Optional[str] = ...,
+        prefix: Optional[str] = ...,
+        dir: Optional[str] = ...,
+    ) -> None: ...
     def rollover(self) -> None: ...
     def __enter__(self: _S) -> _S: ...
-    def __exit__(self, exc_type: Optional[Type[BaseException]],
-                 exc_val: Optional[BaseException],
-                 exc_tb: Optional[TracebackType]) -> Optional[bool]: ...
-
+    def __exit__(
+        self, exc_type: Optional[Type[BaseException]], exc_val: Optional[BaseException], exc_tb: Optional[TracebackType]
+    ) -> Optional[bool]: ...
     # These methods are copied from the abstract methods of IO, because
     # SpooledTemporaryFile implements IO.
     # See also https://github.com/python/typeshed/pull/2452#issuecomment-420657918.
@@ -127,25 +157,24 @@ class SpooledTemporaryFile(IO[AnyStr]):
 
 class TemporaryDirectory(Generic[AnyStr]):
     name: str
-    def __init__(self, suffix: Optional[AnyStr] = ..., prefix: Optional[AnyStr] = ...,
-                 dir: Optional[_DirT[AnyStr]] = ...) -> None: ...
+    def __init__(
+        self, suffix: Optional[AnyStr] = ..., prefix: Optional[AnyStr] = ..., dir: Optional[_DirT[AnyStr]] = ...
+    ) -> None: ...
     def cleanup(self) -> None: ...
     def __enter__(self) -> AnyStr: ...
-    def __exit__(self, exc_type: Optional[Type[BaseException]],
-                 exc_val: Optional[BaseException],
-                 exc_tb: Optional[TracebackType]) -> None: ...
+    def __exit__(
+        self, exc_type: Optional[Type[BaseException]], exc_val: Optional[BaseException], exc_tb: Optional[TracebackType]
+    ) -> None: ...
 
-def mkstemp(suffix: Optional[AnyStr] = ..., prefix: Optional[AnyStr] = ..., dir: Optional[_DirT[AnyStr]] = ...,
-            text: bool = ...) -> Tuple[int, AnyStr]: ...
+def mkstemp(
+    suffix: Optional[AnyStr] = ..., prefix: Optional[AnyStr] = ..., dir: Optional[_DirT[AnyStr]] = ..., text: bool = ...
+) -> Tuple[int, AnyStr]: ...
 @overload
 def mkdtemp() -> str: ...
 @overload
-def mkdtemp(suffix: Optional[AnyStr] = ..., prefix: Optional[AnyStr] = ...,
-            dir: Optional[_DirT[AnyStr]] = ...) -> AnyStr: ...
+def mkdtemp(suffix: Optional[AnyStr] = ..., prefix: Optional[AnyStr] = ..., dir: Optional[_DirT[AnyStr]] = ...) -> AnyStr: ...
 def mktemp(suffix: Optional[AnyStr] = ..., prefix: Optional[AnyStr] = ..., dir: Optional[_DirT[AnyStr]] = ...) -> AnyStr: ...
-
 def gettempdirb() -> bytes: ...
 def gettempprefixb() -> bytes: ...
-
 def gettempdir() -> str: ...
 def gettempprefix() -> str: ...